| Lists: | Postg토토 핫SQL :Postg메이저 토토 사이트SQL |
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| From: | Трофимов Иван <i(dot)trofimow(at)yandex(dot)ru> |
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| To: | "pgsql-interfaces(at)lists(dot)postgresql(dot)org" <pgsql-interfaces(at)lists(dot)postgresql(dot)org> |
| Subject: | About default inBufSize (connection read buffer size) in libpq |
| Date: | 2023-03-05 02:42:06 |
| Message-ID: | 298631677983213@mail.yandex.ru |
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| Lists: | Postg사설 토토 사이트SQL Postg토토 사이트 순위SQL |
<div>Hi!</div><div> </div><div>I was running some benchmarks for PG driver built on top of libpq async functionality,</div><div>and noticed that recv syscalls issued by the application are limited by 16Kb, which seems to</div><div>be inBufSize coming from makeEmptyPGconn in interfaces/libpq/fe-connect.c.</div><div> </div><div>Hacking that to higher values allowed my benchmarks to issue drastically less syscalls</div><div>when running some heavy selects, both in local and cloud environments, which made them</div><div>significantly faster.</div><div> </div><div>I believe there is a reason for that value to be 16Kb, but i was wondering if it's safe to change</div><div>this default to user-provided value, and if it is - could this functionality be added into API?</div>
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| From: | Andres Freund <andres(at)anarazel(dot)de> |
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| To: | Трофимов Иван <i(dot)trofimow(at)yandex(dot)ru>, pgsql-hackers(at)postgresql(dot)org |
| Cc: | "pgsql-interfaces(at)lists(dot)postgresql(dot)org" <pgsql-interfaces(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: About default inBufSize (connection read buffer size) in libpq |
| Date: | 2023-03-06 18:15:11 |
| Message-ID: | 20230306181511.kpje2skz2vhpqz3b@awork3.anarazel.de |
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| Lists: | Postg토토 핫SQL : Postg메이저 토토 사이트SQL |
Hi,
On 2023-03-05 05:42:06 +0300, Трофимов Иван wrote:
> I was running some benchmarks for PG driver built on top of libpq async
> functionality,
> and noticed that recv syscalls issued by the application are limited by 16Kb,
> which seems to
> be inBufSize coming from makeEmptyPGconn in interfaces/libpq/fe-connect.c.
>
> Hacking that to higher values allowed my benchmarks to issue drastically less
> syscalls
> when running some heavy selects, both in local and cloud environments, which
> made them
> significantly faster.
>
> I believe there is a reason for that value to be 16Kb, but i was wondering if
> it's safe to change
> this default to user-provided value, and if it is - could this functionality be
> added into API?
I've observed the small buffer size hurting as well - not just client side,
also on the serve.
But I don't think we necessarily need to make it configurable. From what I can
tell the pain mainly comes using the read/send buffers when they don't even
help, because the message data we're processing is bigger than the buffer
size. When we need to receive / send data that we know is bigger than the
the buffer, we should copy the portion that is still in the buffer, and then
send/receive directly from the data to be sent/received.
Greetings,
Andres Freund